DSS jpg or RAW

[Langy]

With the DSS Software I was wondering what sort of results you would get if you use jpg files rather than RAW.

I know from normal photography that if I have images that I want to alter more than a what a normal jpg can do I would shoot in RAW to start with.

Now when you use DSS it relies on a lot of the recorded data that is not visible as you have to ramp up the curves, I was wondering if that information would still be there if the original image was shot as a large jpg.

I'm using Canon cameras so would expect that the compression on large jpg files would be standard on all models of their camera.

[ronin]

From previous posts and problems it seems that DSS requires RAW.

[leelee970]

You can use jpg but it is compressed data - so some of that data will forever be missing.

RAW simply has all the data.

[lensman57]

With the DSS Software I was wondering what sort of results you would get if you use jpg files rather than RAW.

I know from normal photography that if I have images that I want to alter more than a what a normal jpg can do I would shoot in RAW to start with.

Now when you use DSS it relies on a lot of the recorded data that is not visible as you have to ramp up the curves, I was wondering if that information would still be there if the original image was shot as a large jpg.

I'm using Canon cameras so would expect that the compression on large jpg files would be standard on all models of their camera.

Most of the precious data collected during ungodly hours and with your expensive equipment will be lost due to jpeg compression, you need to use a lossless format like Fits or Raw . 

A.G

[jgs001]

Really, for astro, you need to be shooting raw. You can use jpg's with DSS, and you will get a result, but you lose so much of the data due to the compression down to 8bits, that if you're camera (and it can) shoots raw, you should shoot raw.

[Langy]

Thanks, just thought I would ask the question.

[Alien 13]

I allways shoot both and have used the jpeg version in DSS to practice with when using my other laptop which is a bit slow, its ok for learning the techniques before i run with the RAW versions.

If you look at the histogram of a sub or a stack you will see that only a small part has any usefull data in it this is all there is to work with so RAW is a must.

Alan

[dph1nm]

Actually, although I wouldn't recommend it if you have the choice,  using jpegs works suprisingly well. I have occasionally forgotten to press the RAW button during a session, and while you probably need to remember to take jpeg bias/flats to go with the lights, the stacks out of DSS are quite acceptable.

NigelM

[reddoss]

The consensus of opinion   is to always  shoot in RAW, then process in TIF format. Conversion to Jpeg is usually done to reduce the file size if the image is going to be sent by e-mail or posted on a website that has a file size restriction. As mentioned above the Jpeg conversion process losses data from the original image.

[dph1nm]

I once took some astro images of the same object as uncompressed tiffs and as jpegs, and independently reduced them. The resulting stacks were utterly indistinguishable when displayed on the web. So while RAW is the format of choice, if you have a camera which  only does jpeg do not be put off.

NigelM